Drive belt systems are in widespread use. For example, within the automotive industry, systems consisting of a driver pulley and or pulleys, a driven pulley, idler pulley(s), and a transmission belt are utilized in transmission systems. The belts in use in such applications are composed of a resilient elastomer reinforced with one or more reinforcing members extending therealong. One or more rows of teeth are uniformly spaced apart in the longitudinal direction along one surface of the belt, the opposite surface being substantially smooth and toothless. The teeth positively engage complimentary cavities within a driver pulley and a driven pulley as the belt rotates. The driver pulley and the driven pulley(s) are thus rotated in a common direction in synchronous fashion. The configuration of the teeth and cavities are relatively complex and the performance requirements demanded of the belt are rigorous, making the belts intended for such applications relatively difficult and expensive to fabricate. U.S. Pat. No. 5,209,705 teaches a drive belt, and U.S. Pat. No. 5,421,789 a drive pulley, configured as described and are hereby incorporated herein by reference.
In other applications, it is common to counter-rotate a driven pulley off a driver pulley through the use of a two sided drive belt. Counter-rotation can serve to economize space and is mechanically advantageous in certain system configurations. To achieve such a result, the driver pulley generally drives the belt by engagement with one belt surface and the driven pulley is engaged by the opposite surface of the belt. Counter-rotation of the driven pulley relative to the driver pulley results.
Counter-rotation of a driven pulley relative to a driver pulley in synchronous, positive drive belt applications such as in automotive transmissions has, however, been difficult to achieve. To accomplish such an objective, a fabrication of row(s) of teeth on both opposite surfaces of the belt would be required. The cost of manufacturing such a belt would prove cost prohibitive. Secondly, the required durability and performance criteria needed for such applications would be difficult to achieve with a dual sided drive belt. Fabricating a double-sided toothed belt suitable for synchronous, positive drive belt systems that can effect a counter-rotation relationship between pulleys has, therefore, proven elusive.
The industry, accordingly, remains in need of a method and system for achieving counter-rotation between a driver pulley and driven pulley(s) in a synchronous positive drive belt system. The method and system should facilitate such an objective without requiring a customized drive belt that would be difficult and expensive to fabricate. Moreover, the belt used in a counter-rotational system should meet the same high performance standards and criteria demanded of existing one-sided belts.